7 keys 0 chests, life of OTP
The chest system is a trick to make you spend money to buy keys. You feel "Omg Riot is so good for giving me chests! I just need keys." And you feel like your responsibility to get the keys, so you spend money to buy keys.
3$ here, 3$ there ... zzzzz.
Cheap Tactics
At least SMITE and DOTA2 give you actual stuff for your money.
There are obviously 21 chests there.. BUT OK
I always have 10 chests 0 keys